Waveguide junction



Feb, 21, 1956 c. E. THOMAS, JR 2,735,985

WAVEGUIDE JUNCTION Filed July 21, 1952 I N VE NTOR 0107/9455 506A?? WOM/Kufe ATTORNEY nited States Patent WAVEGUIDEJUNCTION Charles Edgar Thomas, Jr., Middle River, Md'., assigner to The Glenn L. Martin Company, Middlek River, Md., a corporation of'Maryland Application `luly 21, 1952, Serial No. 300,091`

8 Claims. (Cl. S33- 8) This invention relates to a novel waveguide junction especially useful where it is desired to obtain a division of the input energy among several isolated outputs.

It is frequently desirable to obtain radio frequency energy from a single source and to-apply predetermined portions of this energy to each of a plurality of separate units. A typical example is where it is desired to supply energy from a local oscillator to each of a plurality of mixers. At the same time it is obviously desirable that the means used to divide the energy will maintain the various mixers isolated from oneanother so thatthere will be no unwanted inter-action therebetween.

It is an object of this inventionto'provide'awaveguide junction of extremely simple construction andwhich is adapted to divide energy supplied to theinput arm -thereof so that one-half of the energy will be causedtotravel. along one of the output arms andone-quarterof the energy along each of another pair ofoutput arms.

A further Objectis to provide such a junction which is of extremely compact sizeV and which may be readily matchedk so as to avoid undesired waves or reflections in the various arms.

A still further object is to provide such a junction which includes means for obtaining the above-mentioned energy disposition, while at the same time providing means for effectively isolating the various output arms from one another.

Further objects and advantages will become apparent from the following description and claims, especially when taken in View of the appended drawing.

In the drawing:

Figure l is a perspective view of the waveguide junc tion; and v Figure 2 is a sectional taken in the' plane indicated' by the line 2-2 in Figure l.

As is clearly shown in Figure 1 the waveguide junction comprises six arms 1 to 6,- each of which consists of ak sec-- These arms are tion of hollow rectangular waveguide. arranged in opposed pairs, each pairlying' along one of three perpendicularly related axes 7, 8 and 9 intersecting at a point 10 interior of the junction. Each of the waveguide sections or arms includes the usual pair of wide walls, or H-plane walls, 11 and a pair of narrow walls, or E-plane walls, 12, the designation of the walls arising from their relationship to the voltage and magnetic fields when the guide is being employed to transmit electromag netic energy in the dominant or TE-Ol mode. Arms 1, 2 and 3 together may be considered as forming an H-plane T, since their broader walls 11 lie in a common plane, similarly, arms 4, and 6 form a second H-plane T with their broader walls lying in a plane perpendicular to that of the other T. The various walls of the arms are interrupted at the junction so that each of the arms has its inner end opening directly, and without obstruction, into the common junction area 13 immediately surrounding the point 1%.

ln order to match the various arms so that there will be no rellection of energy fed toward the junction through any of` the arms the following arrangement is provided. AV short metal rod 14 is arranged with its axis parallel: to the E-vector of guides 1, 2 and 3 directly opposite the inner end of guide 1- and spaced therefrom substantially asl indicated` in Figure 2. When this rod is properly located it will serveto match all three armsl 1, 2 and 3 so that energy fed into any one of these arms will be distributed as described hereinafter withoutreflection. A similar rod 15` is/ arranged with its axis parallel to the E-vector in the guides 4, 5 and 6 to likewise match these three arms. As is Well known inthe art the length, diameter, and exact location of matching elements 14 and 15V will depend upon the particular range of frequencies thatis to be handled by the junction. For example in one such junctiony using standard one inch by one-half inch wave guide proper matching was obtained overthe frequency bandl from 8500 to 9600 megacycles with the realtive sizes and spacings of the` matching elements substantially as shown in the drawing. To support rods' 14 and l5 an elongated rod 16 is provided, extending along the axis 7 of guides 1 and 4 and being supported at its opposite ends by a pair of rods 17 and 1S located respectively within the guides 4 and 1 andI with their axes perpendicular to the E-vectors within these indivdual guides. With this arrangementv the supporting elements 16, 17 and 18 may also be made of metal without appreciably affecting the transmission of energy through the various arms, while atjthe same time providing a very simple and easily constructed arrangement for supporting the impedance match-- ing rods 14A and 15.-

When the above-describedA junction is properly matched by elements 14'and 15, energy fed into arm 1 willbe die vided equally between arms Zand 3, while energy` fed intoA arm 4 will be divided equally between arms 5 and 6. In the first instance none of the energy will appear in arms 4, Sor 6, while in the second instance none'of the energy willappear inthe arms 1, 2- or 3. Energy lfed into the arm 2 will be divided so'that one-half of it will pass into arml and one-quarter into eachv of arms 5 and 6, with none appearing in arms 3. or 4. Similarly' energy' fed into-arm 3 will be divided among arms 1, 5 and 6, with none appearingy in arms 2 or 4. Also, as'can readily be seen from the symmetry of the junction, energy fed into either arm none goingintothe other pair of arms.

In Figure 1, arm 2 has been` illustrated as the input arm,

` while arms 1i, 5 and 6 are used as the output arms. Arms 3 and 4 are shown as being terminated by matched-loads example, arms 1, 51 and @are to be connected to mixers,

each to receive its proper proportion of energyV from a local oscillator applied to the input arm 2, it is obviously desirable that complete isolation be maintained between the various mixers so that there will be no interaction therebetween. For example, if a slight amount of energy were fed back or reilected from the mixer connected to arm 1, this energy would, as previously described, be divided between arms and 5. That energy going into arm 3 would, if the arm were not terminated with a matched load, be reflected and a portion thereof would pass into arms 5 and 6. Obviously under such conditions each mixer would interact with the others. However, when arm 3 is matched any energy coming toward the junction from arm 1 and passing into arm 3 will be absorbed so that none of it can pass into arms 5 or 6. It can likewise be readily shown that any energy arriving through either arms 5 or 6 and passing into arms 3 or 4 will be absorbed and thus will be prevented from coupling into the other output arms.

This junction when properly matched as described will Paten-tedk Feb. 21, 1-'956 operate to couple, isolate or divide electromagnetic energy as described above so long as the energy is being propagated therealong in the TE-Ol mode, and is consequently usable over a relatively wide band of frequencies. It is extremely compact as manufactured and easily matched. It will be obvious to those skilled in the art that it can be used in many other applications than that of dividing energy for mixing purposes as particularly described. Moreover, While but one particular form of matching has been illustrated, obviously other known matching devices or arrangements could be provided, although that shown has the advantage of being extremely simple to construct, while at the same time permitting a simple but mechanically eicient support therefor. Many other variations will be apparent to those skilled in the art and may be made without departing from the spirit and scope of the invention as defined by the appended claims.

I claim as my invention: t

l. A waveguide junction comprising three pairs of axially aligned hollow rectangular waveguide sections, the axes of said pairs being mutually perpendicular to one another and intersecting at a common point, said sections having their inner end portions joined together to form a cornmon enclosed junction area into which each of said sections open, three of said sections having their broader walls arranged parallel to a common plane and the remaining sections having their broader walls arranged perpendicular to said plane.

2. A waveguide junction comprising six sections of hollow rectangular waveguide having their inner end portion joined together to form a common junction area, said sections extending outwardly from said junction area and arranged in opposed pairs, the axes of said pairs lying along three mutually perpendicular axes intersecting at a common point within said junction area, three of said sections having their broader walls lying parallel to a common plane and the other three sections having their broader walls parallel to a second plane perpendicular to said first mentioned plane.

3. A waveguide junction comprising four sections of hollow rectangular waveguide intersecting one another at their inner ends to form a right-angle cross and with their wider walls lying in planes perpendicular to the general plane of the cross, and fth and sixth waveguide sections having their axes extending perpendicular to the plane of the cross and intersecting the axes of said first-mentioned sections, said fifth section having its wider walls coplanar with the corresponding walls of one pair of said first mentioned sections and the sixth section having its wider walls coplanar with the corresponding walls of the other pair of said first mentioned sections.

4. A waveguide junction comprising a plurality of rectangular waveguide sections having H-plane walls, said sections being arranged to form a pair of intersecting H-plane T-junctions, with the planes of the Ts perpendicular to one another and with the axes of all of said sections intersecting at a common point within said junction.

5. A waveguide junction comprising a plurality of rec tangularwaveguide sections having H-plane walls, said sections being arranged to form a pair of intersecting H-plane T-junctions, with the planes of the Ts perpendicular to one another and with the axes of all of said sections intersecting at a common point within said junction and means within said junction for separately matching each pair of Ts whereby to prevent reection of electromagnetic energy moving along any of said sections toward said intersection.

6. A waveguide junction comprising six sections of hol low rectangular waveguide having their inner end portions joined together to form a common junction area, said sections extending outwardly from said junction area and arranged in opposed pairs, the axes of said pairs lying along three mutually perpendicular axes intersecting at a common point within said junction area, three of said sections having their broader walls lying parallel to a common plane and the other three sections having their broader walls parallel toa second plane perpendicular to said first mentioned plane, and means within said junction area for matching the impedance of each of said sections to that of said junction.

7. A waveguide junction comprising four sections of hollow rectangular waveguide intersecting one another at their inner ends to forma right-angle cross and with their wider walls lying in planes perpendicular to the general plane of the cross, and fifth and sixth waveguide sections having their axes extending perpendicular to the plane of the cross and intersecting the axes of said first mentioned sections, said fifth section having its wider walls coplanar with the corresponding walls of one pair of said first mentioned sections and the sixth section having its wider walls coplanar with the corresponding walls of the other pair of said first mentioned sections, and a pair of impedance matching rods supported within the common intersection of said sections, one of said rods having its axis perpendicular to the broader walls of said fifth section and the other having its axis perpendicular to the broader walls of the sixth section.

8. A waveguide junction comprising a plurality of rectangular waveguide sections having Hplane walls, said sections being arranged to form a pair of intersecting H-plane Tjunctions, with the planes of the Ts perpendicular to one another and with the axes of all of said sections intersecting at a common point Within said junction and a pair of rectangularly oriented impedance match ing rods supported within the common area of intersection of said Ts, each rod having its axis perpendicular to the H-plane walls of one of said Ts.

References Cited in the file of this patent UNITED STATES PATENTS 2,445,895 Tyrrell July 27, 1948 2,501,052 Herlin Mar. 2l, 1950 2,514,679 Southworth July ll, 1950 

